In recent years, portable electronic devices (communication media) called IC cards or smart cards have prevailed remarkably. For example, IC cards are used in various fields not only as credit cards, commuter passes, passports, license cards, and settlements of other commercial trades, but also as ID cards such as employee ID cards, membership cards, and insurance cards.
An IC card incorporates an IC (integrated circuit) chip which has a nonvolatile data memory and a control element such as a CPU. An IC card processing apparatus such as an IC card reader/writer transmits a read command to an IC card to read out data from the IC card, and transmits a write command to the IC card to write data in the IC card.
The IC card includes a plurality of communication units, and can communicate with the IC card processing apparatus via the respective communication units. For example, the IC card can communicate with the IC card processing apparatus via one of a plurality of communication interfaces. Alternatively, the IC card can communicate with the IC card processing apparatus via one of a plurality of logical channels.
For example, when the IC card includes first and second communication interfaces, data stored in the IC card may be unwantedly accessed from both of the first and second communication interfaces. Likewise, when the IC card supports first and second logical channels, data stored in the IC card may be unwantedly accessed from both of the first and second logical channels.